Php 准备语句致命错误

那么，您可以在

$dbh

<?php
//Defining page title
define('WEBSITE_TITLE', 'Register');

//Content location
$content = 'content/register.php';

//Database connection
try {
    $dbh = new PDO('mysql:host=localhost;dbname=saldev', 'admin', '420blazeit');
    $dbh = null;
} catch (PDOException $e) {
    die();
}

//Including website template
include_once 'template.php';


if(isset($_POST['submitRegister'])) {
    $username = $_POST['username'];
    $password = $_POST['password'];
    $password2 = $_POST['password2'];
    $email = $_POST['email'];
    $rank = 'user';


    $ins = $dbh->prepare("INSERT INTO 'users'('username', 'password', 'email', 'rank') VALUES (''username','password', 'email','user')");
    $ins->execute();
    echo 'Success! you have been register';
    header("Location: index.php");
    }
?>

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此外，您不应该在mysql查询中使用表或列名。

您有两个单引号。替换

$dbh = null;

到

---

同时删除

$dbh=null
为什么要编写$dbh=null；？？
$ins = $dbh->prepare("INSERT INTO 'users'('username', 'password', 'email', 'rank') VALUES (''username','password', 'email','user')");

$ins = $dbh->prepare("INSERT INTO users (username, password, email, rank) VALUES ('username','password', 'email','user')");